Green coffee beans are well known to contain a multiplicity of organic compounds. Most of such compounds are not reduced by the process of roasting the coffee beans prior to grinding same for the preparation of coffee. In addition to the various forms of celluloses and carbohydrates, which constitute the major constituents in the natural coffee beans, there also occur in such green coffee beans about 12 to 17 percent by weight on a dry weight basis of a mixture of oils which are fatty acids, including myristic, palmitic, stearic, oleic, linoleic and others. These coffee bean oils, which are carried over by the hot water in which the ground coffee beans are brewed are undesirable in the final beverage for several reasons. First, the oils contribute to the rapid staleness of brewed coffee when kept warm in a container over periods of time since they rapidly develop rancidity and odor. Secondly, such oils are undesired by many consumers because of the possible relation to the development of elevated serum cholesterol levels in coffee drinkers. Therefore, the removal or reduction of the presence of such coffee vegetable oils in the brewed coffee beverage has been long desired.
In addition to the presence of naturally occuring coffee oils, decaffeinated coffee, an increasingly popular form of the coffee beverage, has most generally been decaffeinated by the use of chlorinated hydrocarbon solvents to remove the caffeine alkaloid. After such removal, traces of the chlorinated hydrocarbon solvents remain adhered to the coffee beans or ground coffee and are likewise carried over into the brewed beverage and into instant decaffeinated coffee when prepared from recrystallized or frozen coffee crystals. Removal of the traces of chlorinated hydrocarbons contained in such decaffeinated coffee has also been desired.
The present invention is particularly adaptable for use in removing coffee bean oils from brewed coffee and for removing the traces of hydrocarbon solvents, including chlorinated hydrocarbon solvents, from brewed decaffeinated coffee. Attempts have been made to improve coffee filters in the past, but most have been directed toward removing the ground fines and the like and none has been adapted to remove the coffee bean oils and chlorinated and non-chlorinated hydrocarbons from processed or brewed coffee, see for example, Schollhamer U.S. Pat. No. 3,651,947; Schleyer U.S. Pat. No. 2,224,409; Jepson U.S. Pat. No. 2,864,504; Oakley U.S. Pat. No. 3,266,411: Bartolome U.S. Pat. No. 4,080,299; and Nicholson U.S. Pat. No. 4,497,709.
The process of removing the oils and hydrocarbons from such beverages and other consumable fluids involves the separation of immiscible liquids. The separation of water from organic fluids in which it is not miscible, such as oils, by the use of coalescers is known. For example, it is known that there exists an interfacial tension between immiscible liquids such as water and oil. It is also known that membranes containing very fine interstitial openings when wetted by one of two immiscible liquids will preferentially allow the passage through the membrane of the liquid with which the membrane is wetted, and will reject, or tend to prevent passage of, the other liquid with an opposing force that is proportional to the interfacial tension of the liquids and inversely proportional to the size of the interstitial openings. Several devices have been constructed to utilize this phenomenon of membranes with fine interstitial openings, see for example, Walker U.S. Pat. No. 4,430,222, but none has addressed the problem of removing oils from processed consumables such as beverages. Also, none has utilized the phenomenon discussed above in conjunction with the known phenomenon of the coalescing effects of closely packed, very fine fibers or fibrils, such as displayed by a napped fabric in order to separate oils and/or hydrocarbons in very low concentrations in water or other aqueous solutions. On the contrary, these prior art devices have generally been directed toward the separation of small concentrations of water from oily or hydrocarbonaceous liquids such as gasoline, fuel oil and the like.